powerpc/esdhc: Correct judgement for DATA PIO mode

The logic for the whether to configure for polling or DMA
was mistakenly reversed in this patch:

Commit 7b43db92
drivers/mmc/fsl_esdhc.c: fix compiler warnings

Signed-off-by: Haijun Zhang <Haijun.Zhang@freescale.com>
CC: Sun Yusong-R58495 <yorksun@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>